Is Jev's answer better than the coin?

The site never claims it is. The study it borrows the coin from found heads made people about 25 percentage points more likely to act, and that acting improved later happiness for major decisions but not minor ones, with its author calling the results merely suggestive and the happiness self-reported. This is a comparison toy, and only the coin half is random.

What stops it from answering a question it shouldn't?

Two Noul gates run ahead of the verdict. At 0.5 or more on crisis the page shows where to find help instead of deciding, and below 0.3 on is_yes_no it asks you for a genuine yes-or-no question. Then decide supplies the probability, yes at 0.5 or more, with anything within 0.1 of 0.5 shown as on the fence.

Where does my question go, and who pays for it?

To the author's relay, which forwards it to the TypeSafe API and keeps no copy. It accepts a question up to 200 characters plus up to 1,000 of details, only answers origins it lists, and caps decisions per minute per visitor and input tokens per day. A decision is about 800 input tokens on a pinned jev-1.13.0.

Can I use this without trusting anyone's server?

Yes. Copy .env.example, paste TYPESAFE_API_KEY, then npm start and npm test, with no dependencies to install. To host the relay yourself, run node relay/server.js behind any HTTPS reverse proxy with ALLOWED_ORIGINS, PUBLIC_HOSTS, TRUST_PROXY=1 and a DAILY_TOKEN_BUDGET set, then point RELAY_HOST in docs/app.js at it. Using only the coin sends nothing anywhere.

What study is the coin based on?

Levitt's 2016 NBER working paper 22487, published in The Review of Economic Studies 88 (1): 378-405 in 2021. In 2013 visitors to FreakonomicsExperiments.com who were stuck let a coin decide; across 22,511 usable tosses, heads made people about 25 points more likely to act and about 63% followed the coin at two months.

What are the four questions it asks Jev?

crisis (Noul; at 0.5 or more it shows help instead of a verdict), is_yes_no (Noul; below 0.3 it asks for a yes-or-no question), decide (Noul; the probability of yes, with anything within 0.1 of 0.5 shown as on the fence), and importance (Score; trivial, minor, notable or major). One request asks all four about the same state.

How much does a decision cost, and what leaves the browser?

The model is pinned at jev-1.13.0 and a decision costs about 800 input tokens, roughly three thousandths of a cent. With the coin nothing leaves the browser; with Jev the question and details go to the relay and on to TypeSafe, the relay stores nothing, and history stays in localStorage with no cookies or trackers.

CommunityJev Practices & Patterns

LetJevDecide

Yes/no decision site that asks Jev and a fair in-browser coin and shows whether they agree. One relay call returns a verdict, the probability behind it and how significant a decision Jev thinks it is, behind crisis and not-yes-or-no gates. Plain HTML, no build step, no sign-up.

See highlights

Open github.com

Stars: 1
Language: JavaScript
License: MIT
Published by: Community
Author: choxos
Last verified: Oct 2026

choxos/LetJevDecide

User repository on GitHub

View on GitHub

Ask a yes or no question. Let Jev, or a fair coin, decide.

Forks: 0
Last pushed: Updated Sep 2026

Repo stats from the GitHub API, cached Oct 2026.Homepage

About this project

Stuck on a yes or no decision? Type it in, then let Jev decide, or flip a fair coin. Use it at choxos.github.io/LetJevDecide or letjevdecide.xera.ac. No sign up, no install. Ask Jev. Jev is TypeSafe's System One model. It does not write text; it answers typed questions with probabilities. Your question gets a yes or a no, the probability of yes behind it, and how big a decision Jev thinks it is. Add details with the slider button in the question box and Jev weighs them too.

Quoted from the project's README. Read the full README.

Tagscommunity awesomejev catalog-import

Works forJev for Classification

Used inJev for Software & DevTools

Languages: JavaScript

Highlights

One POST to /v1/systemone asks four questions about the same state in parallel: crisis, is_yes_no, decide and importance, then thresholds them.
The coin is a crypto.getRandomValues flip in the browser, so nothing leaves the machine, and also-flip runs both deciders to compare them.
The relay is deliberately narrow: question up to 200 characters, details up to 1,000, origin allowlist, rate and token caps, no storage.
Plain HTML, CSS and JavaScript on GitHub Pages with no build step and no dependencies; history is localStorage, with no cookies or trackers.

Watch out

This is a toy and the README says so: for fun, not professional advice. The verdict rules are hand-set constants in relay/decide.js, with yes at 0.5 or more, anything within 0.1 of 0.5 flagged as on the fence, a crisis score of 0.5 or more suppressing the verdict in favor of pointing to help, and is_yes_no below 0.3 asking for a proper yes/no question; the model is pinned at jev-1.13.0. Only the coin is random, since Jev's answer depends entirely on the question and details you type, capped at 200 and 1,000 characters. The underlying coin-toss study is described by its own author as merely suggestive, with self-reported happiness and incomplete follow-up. Hosted use depends on the author's relay, so anyone uncomfortable with that should self-host: Node 20+, a TypeSafe key and an HTTPS reverse proxy with an explicit origin allowlist. Copy reviewed against the repository README on 2026-10-04, not from running it.

Questions about this entry

Short answers drawn from the linked project or page.

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